Effect of Al addition on microstructure and mechanical property of Mg-Mn-Ca-Ce based alloy

In this work, the effect of Al addition on the microstructure and mechanical properties of as-extruded Mg-0.6Mn-0.4Ca-0.2Ce-xAl (x=0, 0.1, 0.3 wt%; named as MXE, MXE01A, and MXE03A, respectively) alloys was investigated. The addition of the fifth group element Al changed the type and content of the second phase in the Mg-Mn-Ca-Ce alloys, and both Mg2Ca and Al-Mn nano-phases were precipitated in the Al-containing alloys, but more unfavorable micron-sized second phases were formed in the MXE03A alloy. In the MXE01A alloy, the high density of nanoscale second phases hindered recrystallized grain growth and contributed to the refinement of recrystallized grains to ∼0.94 μm. At the same time, the MXE01A alloy contains a high density of residual dislocations, which become obstacles to the movement of newly generated dislocations. As a result, the yield strength (YS) of the MXE01A alloy reached 330 MPa, and the elongation (EL) was maintained at 17.5 %. The present results can provide important theoretical guidance for the compositional optimization of low-cost and high-performance Mg wrought alloys. •The refinement of recrystallized grains can be promoted by adding an appropriate amount of Al to Mg-Mn-Ca-Ce alloys.•The addition of Al changed the type and content of the second phase, precipitating Mg2Ca and Al-Mn nanophases.•Mg-0.6Mn-0.4Ca-0.2Ce-0.1Al alloy has a yield strength of 330 MPa and maintains an elongation of 17.5 %.